This invention relates to improved gaskets, especially for use with oil pan and rocker covers for sealing them to automotive engines.
To seal oil pan and rocker covers as of die cast aluminum, molded elastomeric gaskets of an "O" ring type are commonly used. They are frequently generally circular in cross-section. Alternatively, such gaskets may comprise at least one parti-circular circumferential portion and generally flattened sides and bottom. To hold such "O" ring-type gaskets in place with the cover for installation, they may be provided with longitudinally spaced, slightly projecting, pairs of friction-type installation tabs which are designed to bear against the opposite sides of a groove in which such a gasket is positioned. The grooves in which such "O" ring-type gaskets are positioned are generally rectangular in cross-section. The grooves are located in the flange of the oil pan or rocker cover and open at the surface of the flange. After insertion of such a gasket in the groove, the cover is juxtaposed with the engine and the flange is bolted thereto with the gasket, which projects slightly beyond the surface of the flange, being in sealing engagement between the flange and the confronting engine surface, thereby to provide a seal.
Because such gaskets are elastomeric, they are usually limp and highly flexible. A number of difficulties of installation result from the use of such gaskets. For example, when a rubber "O" ring-type gasket is to be installed, as in the groove of an oil pan cover flange, it tends to stretch slightly. Thus, when one reaches the end of the endless gasket being installed, a bulge frequently is produced requiring either removal and reinsertion of the gasket, or further manipulation to "spread" the bulge. Further, limp gaskets must be installed by hand and cannot be installed mechanically, as by a robot.
One possible solution to some of these problems would be to provide a molded rubber gasket with a rigid core, such as a metallic wire core or other stiffener. This would provide a gasket of fixed dimensions and length and with sufficient rigidity for a robot to handle and insert the gasket appropriately. However, when such gaskets are in placed and fasteners are positioned and tightened, any excess of torquing load would tend to split the rubber adjacent to the edge of the wire, the gasket would then lose its integrity, and the gasket would tend to fail as an adequate seal. Further, because the sealing flange of the typical oil pan cover is relatively flexible, the fasteners must be pulled down tightly to maintain the seal between the cover and the engine. Even if the torque applied to the fasteners is controlled, it is not realistically possible to prevent rubber splitting. Hence, the typical molded rubber "O" ring-type gasket with a rigid core, such as a metallic wire, is not fully suitable as an effective oil pan cover gasket, and the careful control of torquing loads is not a fully effective solution.
An improved gasket for use in an "O" ring-type gasket environment with improved sealing characteristics, and which may be mechanically installed rather than manually installed, is highly to be desired.